The transmission of data in the form of a pulse-width-modulated signal is described in PCT Publication No. WO 98/05139. In one specific embodiment of synchronized data transmission, two different information pulses and a synchronization pulse are generated using different pulse lengths. In this manner, as a result of the three different states within the context of one pulse-width modulation, both data information as well as synchronization information can be transmitted. In this context, the use of this method, cited in the related art, and the use of the corresponding interface for data transmission is represented in the aforementioned document, in particular, as applied in a motor vehicle, for example, in the connection between a voltage regulator and the electrical system of a motor vehicle, or as the connection between the voltage regulator and the microcomputer of the digital engine electronics as a component of the control unit.
In addition to a multiplicity of other application possibilities, such as in machine tools, i.e., in the area of producer goods, or in the area of commodity goods, it is precisely in the automobile area that, as a result of the continued expansion of electronic systems and their cross-linking, the necessity is increasingly evident of replacing conventional wiring by bus systems and sub-bus systems.
In this context, in particular, as a central main bus system, a CAN bus, for example, is used, to which, in the automobile area, e.g., for the closing system or an electronic window lift system, etc., a sub-bus system is coupled, especially via a gateway.
Sub-bus systems of this type are robust and simple local bus systems, usually having low transmission rates, generally being subordinated to a main bus system such as CAN. Sub-bus systems of this type are generally configured as master-slave systems, the subscriber, or nodes, that carry out the master function frequently possessing the gateway to the superordinate main bus system. Known sub-bus systems in his connection are the BSS system (bit-synchronous interface) and the LIN bus system (local interconnect network). In the case of sub-bus systems such as LIN or BSS, different sub-bus protocols are generally used. This means that the systems use the same physical layer but different data bit codings. Thus in the case of the LIN bus system, a standard NRZ coding (not return to zero) is used, whereas in a BSS bus a phase modeling, specifically a pulse-width modeling, is used as the coding.
Heretofore, sub-bus systems of this type, especially the two aforementioned, have been so different that they cannot communicate when mixed. For the hardware of systems of this type, this results in the fact that either a variant must be selected or the costs for implementation sharply increase. Furthermore, as a result, the flexibility of changing from one to another bus system, or bus protocol, is sharply limited. Thus, heretofore, only special, very expensive electronic circuits, or components, and very expensive software implementations have been capable of imaging a sub-bus protocol, for example using pulse-width-modulated data coding, onto another sub-bus protocol, or onto another sub-bus controller, for example, using asynchronous, binary data coding.
Thus the objective comes about to realize, using a simple arrangement, this type of mixed communication between different bus, especially sub-bus systems.